JP4456299B2 - Anti-theft system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an anti-theft system that protects merchandise displayed in a store from fraudulent acts such as shoplifting, and more particularly to an anti-theft system that uses an alarm sound generated by an alarm unit attached to the merchandise. is there.
[0002]
[Prior art]
Conventionally, stores that display and sell products such as compact disc cassettes, magnetic tape cassettes, and apparel-related products have adopted an anti-theft system as shown in Fig. 4 in order to protect these products from fraudulent acts such as shoplifting. is doing.
[0003]
The anti-theft system is composed of an anti-theft gate (30) installed near the outlet (40) of the store and an alarm unit (20) attached to the product (50). The anti-theft gate (30) includes a circuit board (31) and a transmission antenna (not shown). The circuit board (31) includes a transmission circuit (not shown) that should generate an alarm activation signal for the alarm unit (20). I have.
[0004]
As shown in FIG. 5, the alarm unit (20) includes a buzzer (22), a circuit board (23), a battery (not shown) and the like inside the casing (21), and a plurality of reports are provided on the surface of the casing (21). A sound hole (24) is opened and an alarm activation switch piece (25) is embedded. The operation of the buzzer (22) is controlled by the circuit board (23). When the alarm unit (20) is removed from the product (50), or the alarm unit (20) passes through the anti-theft gate (30). It sounds when you do it. There is also a type in which an alarm unit is attached to a product with a wire instead of the alarm activation switch piece (25). In this case, the alarm unit generates an alarm upon detecting that the wire has been removed, the wire has been cut, or the anti-theft gate (30) has been passed.
[0005]
In the store, the product (50) is displayed on the display stand with the alarm unit (20) attached. When the clerk sells the product (50) to the customer, the buzzer (22) is not sounded by sending a specific reset signal from the alarm ineffective device (not shown) to the circuit board (23) of the alarm unit (20). After setting the state, the alarm unit (20) is removed from the product (50), and the product (50) is handed to the customer in exchange for the price.
[0006]
On the other hand, if the customer removes the alarm unit (20) from the product (50) illegally, the alarm operation switch piece (25) is turned off and the buzzer (22) sounds. Further, when the customer illegally takes the product (50) out of the store together with the alarm unit (20), the circuit board (23) of the alarm unit (20) receives an alarm from the transmission antenna of the anti-theft gate (30). In response to the activation signal, the buzzer (22) will sound.
[0007]
However, the accounting office where the store clerk is located is in the back of the store and is often separated from the vicinity of the outlet (40) where the anti-theft gate (30) is installed. Therefore, it may be difficult to hear the alarm sound from the buzzer (22) at the accounting office.
[0008]
To solve this problem, as shown in FIG. 6, an alarm sound detection device (10) having a microphone (11) is illegally alerted by a customer in the vicinity of the anti-theft gate (30) or in a fitting room. Installed in a place where the unit may be removed and concealed, the alarm sound detection device (10) detects the alarm sound (12) of the alarm unit (20) and generates a new alarm signal (13), An anti-theft system that informs a store clerk of the occurrence of an alarm using a speaker (15) and a lamp (16) installed in an accounting office (14) by a wired or wireless method is supplementarily used.
[0009]
[Problems to be solved by the invention]
However, in the detection of such alarm sound, a disturbance sound approximated to an alarm sound generated from BGM or noise in the store is misrecognized as an alarm sound, or an alarm sound echoing in the store is erroneously recognized as a disturbance sound. There is a problem such as.
[0010]
Therefore, an object of the present invention is to provide an anti-theft system capable of detecting an alarm sound with less misrecognition and capable of detecting with high accuracy.
[0011]
[Means for Solving the Problems]
The present invention relates to an alarm unit that is combined with an anti-theft object and intermittently generates an alarm sound of a constant frequency for fraud, and an alarm sound detection device that detects an alarm sound of the alarm unit and generates an alarm signal In the anti-theft system, the alarm sound detection device has first determination means and second determination means for an input signal including the alarm sound and disturbance sound, and the first determination means includes: The random disturbance included in the input signal is determined, and the second determination means determines the reflected sound due to the reverberation of the alarm sound. In any determination, the input signal is determined to be an alarm sound. In this case, an alarm signal is generated.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a flowchart showing a processing method of an alarm sound detection device showing an embodiment of the anti-theft system according to the present invention, and FIGS. 2 and 3 are schematic diagrams of signal waveforms.
[0013]
The processing method of the present invention will be described below with reference to the drawings.
[0014]
Step 0 (S0) is a standby state (initial state) of the antitheft system. Here, as described in the related art, when the alarm unit is illegally taken out of the store or removed from the product, an alarm sound is emitted from the alarm unit. This alarm sound is shown in FIG. As shown to a, it generate | occur | produces by the buzzer drive signal of the intermittent waveform (period T1, duty 50%) of the fixed frequency f (period 1 / f).
[0015]
In step 1 (S1), the alarm sound of the alarm unit is subjected to disturbance and echo of the alarm sound. As shown in b, the input signal varies in sound pressure value. This input signal is received by the microphone (11) of the alarm sound detection device installed in the vicinity of the anti-theft gate or in the store, and predetermined signal processing is performed in the next step.
[0016]
In step 2 (S2), the input signal (FIG. 2.b) is sent to a filter circuit that passes the frequency around the alarm sound (f: for example, 3.125 KHz) and a predetermined sound pressure value (one point in FIG. 2.b). 2. After passing through a harmonizing circuit that receives the above-mentioned chain line L) and aligns the sound pressure values. The waveform is b2. After that, the alarm sound detection device uses the input signal (FIG. 2.b2) after the wave shaping that has a frequency in the vicinity of the alarm sound and is equal to or higher than a predetermined sound pressure value. A detection signal is created and output as shown in c. Specifically, FIG. After the rising edge of the input signal b2, a pulse waveform is generated for the period T2. (In FIG. 2, the case where the sound pressure value is sounded more than a certain value after elapse of t1 time after the alarm unit sounds the alarm is shown.) After that, the sound pressure value of the input signal is lowered and is again predetermined. When the sound pressure value exceeds the value, the pulse waveform is generated again for the period T2. In the present embodiment, the case where the level fluctuation occurs four times within one cycle of the intermittent period of the alarm sound is shown.
[0017]
In steps 3 to 7, an input sound including an alarm sound and a disturbance sound is determined. That is, steps 4 to 5 are determinations for disturbance, and the frequency of the input signal is measured. Steps 6 to 7 are determinations for the echo of the alarm sound, and the rise time of the detection signal is measured. That is, according to the determination method characterized by the invention, the disturbance sound included in the input signal has a constant frequency f, whereas the disturbance sound does not have a constant frequency. In particular, it pays attention to the fact that the frequency change appears prominently in the period of several tens of pulses. The time for obtaining the predetermined number of pulses is counted several times, and the warning sound or disturbance is observed by looking at the deviation. It is to judge whether it is sound. In addition, fluctuations in the sound pressure value of the reverberant sound due to the reverberation of the warning sound included in the input signal may occur in several patterns depending on the situation of the store, the installation situation of this anti-theft system, etc. The focus is on the existing waveform (the same pattern).
[0018]
Hereinafter, a specific embodiment will be described.
[0019]
In step 4 (S4) and step 5 (S5), the frequency of the input signal (b2) is determined.
[0020]
In step 4 (S4), first, it is strictly determined whether the input signal (b2) after the wave shaping is an alarm sound (frequency f: 3.125 KHz). The harmonized input signal (b2) has been passed through the filter circuit in step 2, but this process is for removing disturbances with extremely different frequencies, and disturbing sounds in the vicinity of the alarm sound frequency. Has not been removed.
[0021]
Therefore, as shown in FIG. 3, in the generation time of the detection signal (T2: 50 milliseconds, for example), the waveform of the input signal is changed to a predetermined number (for example, 30 waves) from the rising time (t10) of the input signal (b2) after wave shaping. Count) and count t11. This is continuously counted a plurality of times (for example, four times) and timed sequentially as t11, t12, t13, and t14.
[0022]
Since the alarm sound frequency is about 3 KHz, it takes about 10 milliseconds, and since it is four times, it takes about 40 milliseconds. The rise time of the detection signal can be adequately handled by 50 milliseconds, but the number of measurements can be changed. It goes without saying that it is a condition.
[0023]
In step 5 (S5), the time differences (t11-t10, t12-t11, t13-t12, t14-t13) are calculated, respectively, and predetermined when each difference value is a normal alarm sound frequency. If it is within the time, it is determined that the frequency is the alarm sound, and the process proceeds to the next step. If any of the differences is not within the predetermined time, it is determined as disturbance noise and the process returns to the standby state (S0).
[0024]
In step 6 (S6) and step 7 (S7), the detection signal (c) is determined.
[0025]
First, in step 6 (S6), each time in the time from the determination operation start (point A) which is the rising point of the detection signal to the rising point (point B) of the detection signal after one intermittent cycle time of the alarm sound of the alarm unit. The rise time of the detection signal is measured (t1, t2, t3, t4).
[0026]
Similarly, the rising of each detection signal within the next intermittent cycle time of the alarm sound of the alarm unit is timed (t11, t21, t31, t41).
[0027]
Next, in step 7 (S7), the difference value (t11-t1, t21-t2, t31-t3, t41-t4) of the rise time for each detection signal within the intermittent cycle time of the alarm sound in step 6 is obtained. Thus, the period (T11, T21, T31, T41) for each detection signal is determined.
[0028]
That is, it is determined whether or not the period (T11, T21, T31, T41) of each detection signal is within the period (T1 ± α time, α is an error time, for example, 10 milliseconds) of the alarm sound, If it is within T1 ± 10 milliseconds, it is judged as an alarm sound. If the period of each detection signal is not within T1 ± 10 milliseconds, it is determined as disturbance noise and the process returns to the standby state (S0).
[0029]
In addition, although the present Example demonstrated in order of step 4-5 and step 6-7, you may perform the process of step 4-5 after the process of step 6-7 simultaneously.
[0030]
In Step 9 (S9), the alarm sound detection device generates an alarm signal and generates a new alarm sound, or an alarm is generated to the store clerk by a speaker, a lamp, etc. installed at an accounting office, etc. by a wired or wireless method. To inform. The alarm signal stop method can be performed by a known method such as a switch or transmission of a stop signal, and the details thereof will be omitted.
[0031]
Further, after step S7 in the processing flowchart of the above embodiment, as a step 8 (S8), a condition of a sensitivity level value that can be arbitrarily set (for example, High = number of repetitions 0, Middle = number of repetitions 1, Low = number of repetitions 2) Determination accuracy can be adjusted by adding a determination (indicated by a broken line in FIG. 1) and repeating the flow of S1 to S7 according to the value. That is, by repeating S4 to S6 once at the sensitivity level Middle and S4 to S6 twice at the sensitivity level Low, the determination criterion is increased, and the sensitivity as the sensor is decreased in this order.
[0032]
In this embodiment, the description of the determination of the frequency of the received sound is omitted because it is possible to determine the number of times according to the pattern of the detection signal, but it is needless to say that this is a design problem and can be variously performed. .
[0033]
The detection signal is also determined by determining the periodicity of each received signal within one intermittent period of the alarm sound. However, it is determined that the rise time of each received signal within one intermittent period is the same in any intermittent period. If it does, it is not limited to an Example.
[0034]
【The invention's effect】
According to the present invention, anti-theft that can be detected accurately with less misrecognition of disturbance noise approximated to alarm sounds generated from in-store BGM, noise, and the like, and alarm sound echoes caused by individual store conditions. A system can be provided.
[Brief description of the drawings]
FIG. 1 is a flowchart showing the operation of an alarm sound detection device showing an embodiment of an anti-theft system according to the present invention.
FIG. 2 is a schematic diagram showing signal waveforms of the present embodiment.
FIG. 3 is a detailed view of FIG. 2;
FIG. 4 is a schematic diagram showing an anti-theft system.
FIG. 5 is a perspective view showing an alarm unit in the anti-theft system.
FIG. 6 is a schematic diagram showing another anti-theft system.
[Explanation of symbols]
a. Alarm signal b. Input signal b2. Input signal after wave shaping c. Detection signal 10. 10. Alarm sound detection device Microphone 12. Alarm signal by alarm unit 13. Alarm signal by alarm sound detection device 14. Accounting office 20. Alarm unit

Claims (4)

  Anti-theft comprising an alarm unit that is combined with an anti-theft object and intermittently generates an alarm sound of a certain frequency for fraud, and an alarm sound detection device that detects an alarm sound of the alarm unit and generates an alarm signal In the system, the alarm sound detection device includes a detection circuit means for generating a detection signal for a certain period of time, a first determination means, and a second determination signal when an input signal including the alarm sound and a disturbance sound is equal to or greater than a predetermined sound pressure value. The first determination means measures the waveform of the input signal a predetermined number and a plurality of times when receiving the input signal, and measures whether a difference between the measured values is within a predetermined time. The second determination means measures the rising time of one or more detection signals generated for each period of the intermittent waveform of the alarm sound, and determines each detection signal. Measure rise period Anti-theft system, characterized in that an alarm signal is generated after determining whether the reflected sound by reflections of the alarm sound in the. The antitheft system according to claim 1 , wherein it is determined whether the sound is an alarm sound by repeating the first determination unit and the second determination unit a plurality of times. A step of generating a detection signal for a certain period of time if an input signal including an alarm sound that intermittently generates a constant frequency for fraud and a disturbance sound is greater than or equal to a predetermined sound pressure value;
Receiving the input signal, measuring the waveform of the input signal a predetermined number and a plurality of times, and determining whether the difference between the measured values is within a predetermined time, thereby determining whether it is a random disturbance sound; ,
Whether or not the reflected sound is due to the reverberation of the warning sound by measuring the rising time of one or more detection signals generated at each period of the intermittent waveform of the warning sound and measuring the rising period of each detection signal. A determining step;
Generating an alarm signal; and
Theft prevention method characterized by including. 4. The anti-theft method according to claim 3, wherein it is determined whether each of the determining steps is an alarm sound by being repeated a plurality of times .

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